One example of traveling carriages which travel on curved surfaces, such as the interior and exterior walls of pipes and ships' hulls, while carrying out certain tasks, such as sand blasting, is disclosed in TOKUKOSHO 60-26752 (U.S. Pat. No. 4,095,378, descriptions and drawings).
The above apparatus has a decompressing housing, wheels as traveling means installed onto said decompressing housing, a suction seal connected to said decompressing housing with its free end caused to be in contact with a traveling surface, and a vacuum-generating means to discharge the fluid trapped inside a decompressed area defined by said decompressing housing, said suction seal and the traveling surface.
When said vacuum-generating means is energized, the fluid inside the decompressed area is discharged to the outside, and the fluid pressure acting upon the decompressing housing due to the pressure difference of the fluid between the inside and the outside of the decompressed area is transmitted to the traveling surface via said wheels, such fluid pressure causing the apparatus to be suction-adhered to the traveling surface.
When said wheels are driven and revolved by a driving means, such as an electric motor, during such suction-adherence state, the apparatus travels on and along the traveling surface by way of the action of the wheels.
Installed onto such apparatus is a task-performing piece of equipment, such as sand blasting equipment which jets a cleaning and polishing agent onto the traveling surface.
Such apparatus of prior art as described above has the following problems to be solved.
In the case that the traveling carriage of prior art is equipped with four wheels, one of such four wheels breaks away from a traveling surface while traveling on and along the surface of a curved object, such as the interior and exterior walls of a pipe and a ship's hull, because the apparatus does not have a frame structure whose shape changes with flexibility, resulting in a constantly unstable position, or resulting in a traveling carriage which does not have sufficient driving power due to the fact that not all the four wheels are in contact with the traveling surface.
In the case that the traveling carriage of prior art is equipped with two sets of caterpillars, one of the four belt wheels, for example, which support such two sets of caterpillars breaks away from a traveling surface, resulting in a constantly unstable position, or resulting in a traveling carriage which does not have sufficient driving power due to the fact that not all the four wheels are in contact with the traveling surface.
In order to solve such technical problems, the present invention aims to provide a traveling carriage which travels curved surfaces and is equipped with four wheels, for example, with none of such four wheels breaking away from, and all of the four wheels being in contact with, traveling surfaces, thereby enabling the apparatus to travel in a stable position or to have sufficient driving power.
The present invention also aims to provide a traveling carriage equipped with two sets of caterpillars with none of the four belt wheels which support such two sets of caterpillars breaking away from, and all of the four wheels being in contact with, traveling surfaces, thereby enabling the apparatus to travel in a stable position or to have sufficient driving power.
In order to solve the technical problems, the present invention also aims to provide a traveling carriage which suction-adheres to, and travels on and along, a traveling surface owing to the pressure of ambient fluid, such as air or water, and is capable of traveling on and along curved surfaces in a stable position or has sufficient driving power.